Riveting machine



Feb. 1o, 1931. C. KNOTH 1,791,505

RIVETING MACHINE Filed Oct. 29, 1924 3 Sheets-Sheet l uw 212s i I /24 /9 ,-i 225,2v /8 /0 ze 1./ 4 H/S HTToQ/VEY Feb. l0, 1931. c. KNoTH RIVETING MACHINE Filed Oct. 29, 1924 3 Sheets-Sheet 2 Fig. 4.

/M/E/VTOQ; 60m2/4D K/VOTH,

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Patented Feb. 10, 1931 NHT-D STE AEN?? FFEQE CONRAD KNOTH, 0F HILLSIDE, NEW JERSEY, ASSIGNOR TO GENERAL MOTORS CGR- PORATION, OF DETROIT, MICHIGAN, A CORPORATIGN OF DELAWARE RIVETING IVIACHINE App1ication 1ed ctober '29, 1924. Serial No. 746,560.

This invention relates to riveting machines and is herein shown as embodied -in a inachine for automatically riveting a circular series ot tie-bars to the end rings of a rollei' c bearing cage.

One Well known form of roller bearing cage comprises opposite end rings joined and spaced .by a circular series of riveted tiebars. Hitherto7 it has been the practice to place one or both of the end rings and the tie bars, in a holding ring or block and then move the block by hand to present the projecting ends ot' the tie bars one-by-one to a riveting tool. The operation is very fatiguing due to the vibration induced by the riveter and the Operator must consequently use bothhands to turn the block and hold the end ring on the tie-bars.

An object of the invention, therefore, is 2 vto provide an improved machine for heading a series of bars. Another object is to provide a machine for automatically securing a circular series of tie-bars to end rings. Another object is to eliminate or decrease the fatigue of the operator in performing this operation and to increase the output. Still another object is to provide apparatus for controlling or feeding tie-bar holders in accoi-dance with the tie-bar spacing and to au- ;ic tomatically stop the holder and the riveter at the end of a predetermined. number of riveting operations. Yet another object is to provide improved apparatus for use in making-roller bearing cages of dili'erent diameters, dierent lengths or cages wherein the tie-bars are diiierently spaced orvary in number.

To these ends and also to improve generally upon devices of the character indicated my invention consists in the various matters hereinafter described and claimed.

Figure l is a side elevation of the machine With some parts in section and some removed.

Figure 2 is a front elevation with some parts omittedtor clearness. f

Figure 3 is a planl View of the machine With some parts omitted.

Figure 4 is a side elevation of a detail.

5'3 operat-ion Work holder.

Y Figure 5 is a sectional view otl a iirst- Figure 6 is a detail view of a sccoiidoperation Work holder.

Figure 7 is a detail View of a secondoperation Work holder adapted :tor use with a diiizerent cage.

Figure 8 is a p steadying device.

lan vieW of a centering or Figure 9 is a side view ot the latter with parts in section.

Figure l() 1s a p lan view of a detail.

Referring to the drawings, the numeral l0 indicates a frame or standard to the upperv end of which is fixed a frame piece or head l2 having an overhangiiig arm 14 which guides a reciprocating plunger 16 having a riveting tool 18 at the lower end. The

plunger is operate-d by a lever 2O pivoted vat the top of the head 12 and rapidly oscillated by connections to by a pulley 22.

a horizontal shaft driven rlfhe rivetingtool i8 is started and stopped by any suitable clutch control 24 actuated in one direction by a spring 26 and actuated in the other direction by a cable or chain 28 connected to the clutch control 24 and to a bracket 80.

A support 34 for the Work and some of the operating mechan ism is slidably mounted for vertical adjustment on Ways 36 on the standard l0, and elevati 1i o' screu7 38 and hand Wheel 40 serving to raise and lower the support. The hub or" the hand Wheel 40 rests on a vertical upright 42 and is grooved and retained thereon by the forked end of an angle plate 43 .fastened to the upright.

it the tcp ot the support 34 is a horizontal slidetvay 44 having undercut edges to slides i'rom front receive a carrier 46 Which to rear ot the machine. et

gib 48 (Figure 2) is removably iixed to the carrier so that the latter can be` easily rcmoved from the slideway.

by a vertical stud shaft 58 having a g clamping nut G2' at the upper end. T he engagement of the washer 56 with the extension 54 provides a friction drive.

The turntable` is intermit- (lll:

`iu the support SLi.

tently turned to carry a circular series of rivets or tie-bars, supported in a suitable holder, beneath the riveting tool. The gear 60 meshes with a bevel gear 66 having its hub splined to the rear end of a horizontal shaft (3S, said hub being rotatably mounted in a lug depending from the carrier 46. The bevel gear 66 is maintained in mesh with the gear 60 by being confined between the latter and the depending lug 70 so that driving engagement is maintained in spite of front t rear movement ofthe carrier, as when adjusting the latter for cages of different diameters. The shaft G8 has a collar 7 2 at the front end to hold it against rearward movement and has keyed to it a bevel gear '2i driven by a bevel gear 76 on a vertical shaft 78 ournalled The vertical shaft 76 has a bevel gear 80 at its lower end driven by a bevel gear 82 on a horizontal shaft 8i journalled in the support 34 and intermittently tuined by a ratchet 86 and a pawl 88 which swings with an arm 90 the hub of which loosely surrounds the shaft. When the pawl is at its forward limit of movement, it strikes against a iiiied stud 92 which liams the pawl inwardly against the face 94 of the ratchet tooth, the front face of the pawl also fitting the radial face 96 of the tooth and7 inasmuch as the face 94; is ,inclined inwardly towards the center of the ratchet` the ratchet is held positively against any further movement. As will. later appear, the riveting operations are performed on different numbers of tie-bars and.y accordingly, the step-by-step turning movement o the ratrhetcan be variedifroni a short feed to a longer one. A shield 9S is tnrnably mounted on the shaft 8% and carries a plate 100 which is desigmd to be placed in the nath of the pawl 88 to enable the lat-ter to feed one or more teeth as desired, the shield being slotted and having` in the slot a threade d 102 en ged by a nut by which the shield can be clamned in the desired position. The number of teeth on the ratchet is the same as the number of ti ibars to be riveted or a multiple thereof and the shield plate is used to uncover more or less teeth for feeding.i dei'ling on the number of tie-bars in the se The ratchet is removable however and is replaceable by another having a diiierent number of teeth. if the number of tie-bars in the series to be riveted is not commensurate with the number of teeth on the first ratchet- The arm 96 is oscillated by a linl: 104 which is attached at its rear end to a slide bar 106 which is slotted to embrace and be guided on a driven stub shaft 10S. T he stub shaft 10S is journalled in the support Se and carries a cam 110 at the end7 engaging a roller 112 on the slide bar 106, a spring 111i fined to the support 34 and to the link 164; holding the roller against the cam. The rear ot the slide bar 106 carries a right angular plate 116 which engages behind the tlexible clutch controlling connection 28, above referred to, so that the movement of he ratchet n chanisin controls the starting and stopping of the riveting tool. rl`he cam lit) makes one revolution to effect each intermittent feeding movement of the ratchet and the turn table, and it starts the operation of the riveting tool at the end of each feed movement, the angular plate 116 at suoli times pulling on the ilexible connection 28 and subsequently releasing it to stop the rivetcr while the next feed is taking place.

The horizontal stub shaft 108 is rotated by a worm wheel in the casing 118` said worin wheel being driven by a worin 120 keyed to a vertical shaft 122 by a spline 121i, this' con4 nection providing for the driving of the worm in different vertical positions of the sliding suppoit 34. The shaft 122 has a thrust collar 126 near the lower end and is journalled at the top in a casing 12S which houses spiral gears 130 and 132 the latter being on a hori- Zontal driving shaft 134: driven by a pulley 136 and having a suitable clutch 1% by which it can be started and stopped. The clutch 138 is controlled by the end of a le y'er 14.0 pivoted at 142 on the frame and having its lower end slotted t 144 and pivotally connected to a link 1&6 having a linee pad at its front end. The linlt has a slot guided by a stud 150 on the support and also slotted to embrace and slide on the shaft above referi ed to. The slot 14:4 in the lever provides for the operati-on of the clutch in diii'erent vertical positions of the worl; carrying support The link 146 carries a. roller 154 arranged to ride on a periphezal cam 156 fixed to the shaft Sli and interimtently turned by the ratchet mechanism. spring 158 fixed to the link i426 and to the frame holds the roller 154 against its cam 156 and tends to make the roller ride into a recess of the cam at the end of a predetermined number of riveting operations depending on the number of teeth on the ratchet or the number of feed strokes of the pawl necessary to complete a rotation of the raf het.

The bevel gears all have the saine number of teeth so that a complete rotation of the ratchet eifects a complete rotation of the turntable and the piece of work thereon. is apparent that the riveting tool o; r ated a plurality of times against each or tiebar, at the end of each feeding movement, and that it is stopped while the turntable and work piece are bein turned to brin g another rivet or tie-bar under the tool. lllheii the last feeding movement is completed, the recess in the cam 156 reaches the roller 1li-i. and, in the absence of some mechanism to prevent it, the roller would ride into the recess of cain 156 and stop the rotation of shaft 1% which rotates the cam 110. Hence the rivet ing tool would continue to operate eciiuse the cam 110 would not be turned to bring its recess opposite its roller 112 to thereby release the flexible clutch controlling connection 28. Mechanism is therefore provided t-o temporarily keep the roller 151 out of the recess in cam 156 so that the cam 110 will be turned far enough to allow the riveting tool to stop. This mechanism comprises a bail made in connected sections 160 and 162, the former having pins 164 extending` into the hub of the pawl carrying arm 90 so that every swinging movement of the arm 90 swings the bail and causes a tail portieri or arrester 166 thereon to move into the path of roller 154. Of course, all of these swinging movements are idle except the last because it is not until the last that the recess in cani 156 reaches the roller 154. Overfeeding of the turntable is further prevented by the provision of a wooden friction blocl: 168 which is pressed by a spring 170 against the periphery of the turntable, the spring being carried in a sleeve 172 and being adjustable by means of a tapered screw plug 1'? 1n the operation of securing a. circular series of shouldered tie-bars to the end rings of a roller bearing cage, some mechanism is needed to hold the bars and the rst end ring assembled during the first riveting operation. ln Figure 1, there is shown a series of shouldered tie-bars 180 to be ivejted to an end ring 182. To take the thrust of the riveting tool the shoulders at the lower ends of the tie-bars rest against a hardened plate 186 which is fastened to an appertured bar holding ring 184 by means of suitable dowel pins and screws 188. The openings in the ring 18e t all sides of the bars and lsupport the bars against lateral displacement during riveting. r1`he lower reduced ends of the tie-bars, to be subsequently riveted project down` Wardly into holes `on the plate 186. rllhe plate 186 is held by a key 190 on a cylindrical core 192 j nojecting upwardly from a base plate 19d which has an annular supporting surface for the hardened plate and the bar holding ring. rl"he`base plate 19st is pro-- vided with an undercut groove 196 adapted for detachable and sliding` engagement with the slide 52 on the rotatable turntable. The

slide is turned to a front-tomar position when the base plate is slid on or oil. rEhe bar holding 'ring 184 has an annular recess 198 which forms a shoulder engaged by a circular plate 200 clamped to the core 192 by a. clamping stud 202.

The carrier 46 is slidable from front to rear on the support 84 and heldin adjusted position by two spaced adjusting screws which abut against opposite sides of a lug 204 (Figure 2) on the support 84. @ne of these screws is indicated at 206 and iscarried by a. plate 208 having a tongue bolted in a longitudinal slot 209 in the side of the carrier. This adjustment is used so that, when cages of slightly different diameter 'from lthat shown are to be operated on, the circle of the tiebar series can be brought directly under the tool. In such cases, the bar holding ring 184 and hardened plate 186 are removed and replaced by others of the required diameter. ln case of any great variation in the diameters of the cages, the base plate 194, the holding ring 184i and the plate 186 are entirely removed and replaced by others. Any small differences in the lengths of the tie-bars ,of different cages is compensated for by elevath ing or lowering the support 3/1- by means of the screw 38. lWhcn the tie-bars are very long and would project so far above the ring 184 that there would be danger of them buckling under riveting pressure, the ring 184 is removed and replaced by a thicker one such as shown at 184A in Figure 5.

lnasmuch as the rapid reciprocation of the riveting tool causes considerable vibration of the Work, a pair of hold-downs are adjustably mounted so as to overlie the end ring 182 close to the projecting ends of Ithe tie-bars. Each hold-down comprises a circular plate or foot 210 having an eccentric stud 212 rotatably and slidably mounted in a hollow sleeve 214i on the forward end of an arm 216 which is bolted by means of the bolts 218 to the overhanging arm 14 above described. The bolted portion of the arm 216 has an enlargement 217 fitting between the webs 220 of the overhanging arm lll to hold the arm rigidly in place. The eccentric studs 212 are fastened in their adjusted positions by clamp` ing screws 222 which have flattened faces enthe shanlrs of the studs.

1n Figure 6 there is shown a device for holding a circular series of tie-bars after they have been riveted to a first end ring and while they are being riveted to a second end ring. rlhe lirst end ring 224` to which tie-bars 226 have already been fastened is arranged to rest upon a hardened plate 228 surrounding a core 230 whichproject-s upwardly from a base plate 232. V'lhe base plate and core of the first holder, shown in Figure 5, maybe used if desired. Rollers 23st of the roller bearing are first sleeved over `he tie-bars and then asecond end ring 236, which is to be riveted to the tie-bars, is placed over the reduced, projecting ends of the tiebars, said rollers then iitting curved grooves 288 in a detachable sleeve 240 which surrounds the core and is connected to it bv means of a key 242. The base plate 232 has an undercut groove 211e to fit the slide 52.

lllhen the cages differ a little in diameter from that shown, the sleeve 240 is removed and replaced by another of a different thickness, tlie carrier 46 then being slid from front to rear as before to bringthe tie-bars d' 'ectlv under the rivetingl tool. Small dili'erences in the lengths of tic-bar series is compensated forasbefore, by elevating or loweringthe support In case ot very long tie-bar series, a longer sleeve such as shown at 24H3 in Figure 7 may be substituted 'for the sleeve 240. In case o tie-bar series of considerable dilierence in diameter the base )late is replaced by another ot' the required size. It will be noted that the tirst end ring Qi to which the bars 226 have been riveted acts a bar holding ring during the operation of attaching the second end ring. The rollers 225i by extending into the grooves 23S act to ltey the to the core Q and allow the cage to be positively rotated. This construction also properly indexes the tie-bars so that they come under the riveting tool. ln the particular bearing shown, the rollers are sleeved on the tie-bars but the holder is adapted Ytor other bearings, such as the type in which the roilers are held between opposite projections or tents on the end rings, between the tie-bars.

l\\Iecha.nism is also provided to steady the rotary base plate and Work holder during the riveting operation and to center the same 3 on the turntable 50. A shown in Figures 8 and 9, two rear steadying lingers 250 and two front steadying iingers Q52 are provided, each rear ting-er being iongitudinally slotted to slide along` a clamping stud Q56 fastened to a curved bar 258 secured by boits 260 to the carrier lihe front fingers are similarly fastened to a curved bar QFZ Which is pivoted at 264 to a bracket 266 fastened at one side ot the carrier and having a fiat tace. or shelf 26S `which supports the curved har when it is swung outwardly to allow one of the base plates and work holders to be installed on the turntable. T he lingers are shown in their outermost positions to surround a base plate. and .vorl holder of large diameter as indicated by the dot and dash line in Figure 8. For the smaller holders, the fingers are moved radially inwards and clamped in a liXed position. rihe fingers merely contact lightly with the holder to steady it 'ithout interfering with its rotation.. The curved bar 26:2 has a hardened latch plate 270 near one end adapted to Je engaged by a hook 272 on a latch lever 2te, pivoted at 276 between cheeks on a bracket 27S. and normally pressed down to a latching position by a spring 28() housed in the bracket and eng ing the short end or' the latch lever. The iront ot the latch hook has an incline 282 to ride up over the latch plate 210 and a plug 284 backed up by a spring s ivcs as a cushion tor the curved plate when it is swung into latched position. The latch lever has a rift pin 288 by which it can be lifted when swinging the curved bar 262 to one side to take olif a work holder. The curve/r. bar 262 manipulated by a handle Q86. Although the invention has been described by reference to a sp vxcii'ic machine, it should be understood that, in its broader aspects, the

invention is not limited to the particular machine selected for mere illustrative piu poses.

I claim:

l. In apparatus of the character described, a riveting tool, means for reciprocating` the tool, a movable holder for supporting a scries of bars to be headed, said holder comprising a member having openings fitting all sides of the bars, and mechanism for intermittently moving the holder to bring the l successively to the riveting tool, and means for automatically stopping the reciprocation olf said riveting tool during the intermittent movement ot the holder; substantially as described.

2. In apparatus o'l the character described, a riveting tool, means for reciprocating the tool, a holder for supporting a circular series of bars, mechanism for intermittent-ly turning the holder to carry the bars successively to the riveting tool, a cam driven by said turning mechanism, and means operated by the cam for intermittently starting the tool reciprocating means; substantially as described.

3. In apparatus of the character described, a riveting tool, means for reciprocating the riveting tool, a clutch for controlling said means, a lined member, a flexible connection from said clutch to said fixed member, a holder for bars to be riveted, mechanism for moving said holder, and a device controlled by said mechanism for engaging said flexible connection and operating the reciprocating means; substantially as described.

4. In apparatus of the character described, a riveting tool, means for operating the tool, a holder for supporting a circular series of bars, mechanism for intermittently turning the holder to carry the bars successively to the riveting tool, a pair of cams driven by said turning mechanism, means controlled by one of said cams for intermittently starting the tool operating means, and means controlled by the other cam for stopping the intermittent turning' movement; substantially as described.

5. In apparatus of the character described, a rivet-ing tool, means for operating the tool, a holder for supporting a circular series oi bars, means for intermittently turning the holder to carry the bars successively to the riveting tool, means for stopping the holder after a predetermined number of turning movements, and means for stopping the operation of said riveting tool after a predetermined number of riveting operations; lsubstantially as described.

6. In apparatus of the character described, a riveting tool, means for operating the tool, a holder for supporting a circular.' series of bars, means for intermittently turning the holder to carry the bars successively to the riveting tool, and means 'lor varying the ex lou llU

tent'y of said intermittent turning movement for differentseries of bars; substantially as described.

7. In apparatus of the character described, Ia riveting tool, means forv operating the tool, a holder tor supporting a circular seriesot bars, mechanism, including a ratchet and paWl, for intermittently turning` the holder to carry the bars successively to the riveting tool, and a movable shield overlying a portion of the ratchet in the path of the p'aivl to vary the extent of the intermittent 'turning movement; substantially as described.

8. ln apparatus of the cl'iaracter described, a riveting tool, means for operating the tool, a holder for supporting a circular series of bars, means for intermittently Vturning the holder around an axis to carry the bars successively to the riveting tool, and means for changing the position of the axis of the holder with respect to the tool; substantially as described.

9. ln apparatus of the character described, a riveting tool, means for operating the tool, al holder for supporting a circular series of bars, means for intermittently turning the holder to carry the bars successively to the riveting tool, and a sliding carrier for adjusting the holder transversely with respect to the riveting tool; substantially as described.

lO. In apparatus of the character described, a riveting tool, means for operating the tool, a rotary holder for supporting a series of bars, means for intermittently turning the holder to carry the bars successively to the rivet-ing tool, a horizontally sliding carrier for the holder, and means for changing the level of the carrier; substantially as described.

1l. ln apparatus of the character described, a riveting tool, means for operating the tool, a rotary holder for supporting-a series of bars, means for intermittently turning the holder to carry the bars successively to the riveting tool, a laterally sliding carrier for the holder, and a detachable connection between the laterally sliding carrier and the holder; substantially as described.

12. ln apparatus of the character described, a riveting tool, means for' operating the tool, a holder tor holding a circular series ot bars, a turntable supporting the holder, means tor intermittently rotating the turntable to carry the bars successively to the riveting tool, and a tongue on the turntable toi' detachably and selectively securing various holders; substantially as described.

l. ln apparatus of the character described, a riveting tool, means for operating the tool. a holder Jfor supporting aw circular series ot bars, a turntable supporting the holder. means for intermittently rotating the turntable to carry the bars successively to the riveting tool, means on the turntable tor selectively'securing variousv holders, and a laterally sliding carrier for the turn table; substantially as described.

14. ln apparatus of the character described, a base plate having an annular sup porting surface, and a bar-holding ring for said base plate to support a series ot bars, said ring being removable and replaceable by a ring ot differentthiclrness to support a series ot oars ot ditlerentlength; substantially as described.

15. ln appara-tus of the character described, a .vorlr holding member for circular series of bars to be riveted, said member having a core, and a detachable sleeve interposed in the space between the core and a selected series ot bars; substantially as described.

1G. ln apparatus ot the character described, a ivorl; holdingA member for a series ot bars to be riveted, said member comprising s a base plate having 'a central core and an annular supporting surface, and mechanism for rotating the member; substantially as described. v

17. ln apparatus or" the character describ'echa ivorlr holdingmember Vfor a series ot bars to be riveted, said member comprising a basepl'ate having an annular supporting surface, anda hardened ring interposed between the annular supporting` surface and a circular series oit bars; substantially as described.

18. In 'apparatus ot the character cescribed, a Work holding member for series of bars to be riveted, said member comprising a base plate having a central core and an annular supporting surface. and a bar holding ring for surrounding' said core to support a circular seriespot bars, said bar holding rin g being removable and replaceable by a ring of diliierent thickness for supporting' a circular series of' bars of another length; substantially as described.

19. In apparatus of the 'character described, a Work holding member for a series of bars to be riveted, said member comprisbase plate having a central core and an annular supporting surface, a sleeve interposed between tlie core and a circular series ot'bars, and a ring interposed between the annular supporting surface and said series of bars; substantially as described;

Q0. ln apparatus ci the character scribed, avorlr holding` member for of bars to be riveted, said member comprising a base plate having a central core and au i. nular supporting surface, a bar holding ring surrounding the core and holding and spa ing a circular series of said bars, and a hardened ringinterposed between the annular s1 porting surface and the bar holding ring, substantially as described. i

2l. In apparatus ot the character described` a plate having a series et openings for holdingand'spacing a series ot shouldered/tie bars, and a plate having a hardened eurtace to support the shoulders of said tie bars against riveting pressure; substantially as described. Y

22. In apparatus of theV character described, a ring having a circular series of openings for holding and spacing a circular seiies of tie bars, a ring having a hardened surface to support said tie bars against rivet ing pressure, anda member having an annular surface to support said rings and a cylindrical core to center said rings; substantially as described. ;V Y

Q3. In apparatus of the character Ydescribed, a base plate having a central core and a flat annular tace, a bar holding ring .having a series of openings for the tie bai's and a shouldered recess, a circular plate hitting the recess, and a clamping screw between the core and the circular plate; substantially as de scribed.

2li. In apparatus oi thev character dee scribed, a riveting tool, means .tor operating the tool, a Work holder for a series oi "rie bars to be riveted to anV end ring, means lor i rotating the Work holder, and a hold-down plate at one side of the riveting tool and overlying the end ring; substantially as described.

In apparatus ot the character dcscribed, a riveting tool, means for operating i the tool, a Work holder for a series of tie bars to be riveted to an end ring, means for rotating the Work holder, a hold-doivn plate at one side of the riveting tool and overlying the end ring, and means or'fixing the plate in diilerent positions in a horizontal plane;

substantially7 as described.

9.6. In apparatus of the character described, a riveting tool, means for operating the tool, a Work holder for a series of tic bars to be riveted to an end ring, means for rotating the Work holder, a hold-down plate having an eccentric stud, and means ior chunping-the stud in different angular positions; substantially as described.V

2'?. In apparatus of the character described, a riveting tool, means for operating the tool, a Work holder for a series oit tie bars to riveted to an end ring, means for rotating the work holder, a hold-down plate at one side oi the riveting tool. and overlying the end ring, said plate having an eccentric stud, a supporting arm rotatably andslidably carrying the stud, and means for clamping the stud in different angular positions and at different levels; substantially described.

28. In apparatus ot the character described, a riveting tool, means for operating the tool, and mechanism for presenting a circular series of tie bars successively to the tool, said mechanism comprising a slidable base plate, a turn table supporting the base plate, and a plurality et holding fingers radially adjustable towards and from tlie base plate to center the latter on the turn table; substantially as described,

29. In apparatus of the character described, a riveting tool, means for operating the tool, and mechanism for presenting a circular series of tie bars successively to the tool, said mechanism comprising a slidable base plate, means for slidably supporting Vthe base plate, a pair of holding lingers at one side of Vthe base plate, and a swinging carrier for other holding lingers at the other side of the base plate; substantially as described.V

30. In apparatus of the character described, a riveting tool, means for operating the tool, and mechanism for presenting a circular series of tie bars successively to the tool, said mechanism comprising a slidable base plate, means for slidably supporting the base plate, a pair of holding lingers atone side of the base plate, and a swinging carrier for other holding fingers at the other side ot the base plate, and a latch for holding and rcleasing the swinging carrier; substantially as described.

In testimony whereof lf hereunto 'affix in v signature. Y Y

CONRAD KNOTH. 

